Is Low-load Resistance Training With Blood Flow Restriction More Effective Than Traditional Rehabilitation of Military Personnel With Lower Limb Injuries

5-RM assessment on leg press and leg/knee extension machines (leg/knee extension pre-intervention only) to assess the participants strength, and inform % load for intervention period.

Testing procedure: 5-minute cycling warm up, followed by 10-rep exercise specific warm up, and then successive attempts at performing a 5RM on injured limb only. The authors acknowledge that due to the likely interference effect of a pain response, performing a \'maximum effort\' physical task in a lower limb injured cohort is unlikely to yield a true measure of MSK performance. It is more accurate to describe outcome scores as providing an \'indication\' of participant performance and progression. We will highlight this as a potential weakness in our study but feel this is a challenge in the measurement of muscle force / strength in all MSK injury research. All outcomes measured will be implemented and recorded based upon a best effort at the time of assessment.

To assess the feasibility and tolerability of the BFR-RT interventions, a participant monitoring booklet will be used throughout the intervention period. The Numerical Pain Rating Scale (NPRS) for injury-specific pain and localised muscle soreness will be collected pre-intervention, immediately post-intervention, and 1-hour post-intervention for each BFR-RT session.

To assess the feasibility and tolerability of the BFR-RT interventions, a participant monitoring booklet will be used throughout the intervention period.

Sessional Rate of Perceived Exertion (scored 0-10; 0=no effort, 10=maximal effort) will be collected following each BFR-RT session.

To assess the feasibility and tolerability of the BFR-RT interventions, a participant monitoring booklet will be used throughout the intervention period.

To quantify training load, the following calculation will be conducted following each BFR-RT session; sets x reps x load (kg).

Specific Example:

BFR-RT Leg Press at 25kg

1 set x 30 reps + 3 sets x 15 reps = 75 reps 75 (reps) x 25 (kg) = 1875 (training load)

The Copenhagen Hip and Groin Score is a patient administered, multi dimensional, pain assessment tool commonly used to assess symptomatic and functional burden associated with hip and groin pathology. Scored from 0-100, lower scores on the HAGOS represent greater symptomatic and functional burden. The MCID per domain is 8, 8, 9, 10, 11, and 12 points for hip-related QOL, symptoms, pain, sport and recreation activities, ADL, and participation in physical activities, respectively.

The LEFS is a patient-reported outcome measure that measures functional status in patients with lower limb musculoskeletal injury. Ability to perform 20 activities, ranging from walking to running on uneven ground, are self-reported from 0-4 with higher scores indicating better function.

To assess the feasibility and tolerability of the BFR-RT interventions, a participant monitoring booklet will be used throughout the intervention period.

Daily morning wellbeing questions (fatigue, muscle soreness, sleep quality, stress levels and mood) will be asked each morning using a Likert scale (1-5), before the first BFR-RT session.

The isometric mid-thigh pull is a test that can assess multiple derivatives of maximal lower-limb muscle strength including, peak force, rate of force development and limb asymmetry. The participant is asked to stand on force plates (set within a mid-thigh pull rig) and then pull on the mid-thigh bar at maximal force.

Pressure pain threshold assessment can help define regions of mechanical hypersensitivity, a common trait of central sensitisation. By utilising a digital pressure algometer (1cm^2 probe, Model FPX 50, Wagner Instruments, USA), the amount of pressure at which the sensation of pressure becomes unpleasant is deemed the PPT, with lower pressure values being indicative of central sensitisation.

The Foot and Ankle Disability Index is a 26-item ankle and foot specific, patient- reported, questionnaire which considers ADLs, function, pain and sleep. Each item is scored from 0 (unable to do/unbearable pain) to 4 (no difficulty at all/no pain), with a total point value reaching a maximum of 104; however, the PROM is scored as a percentage and a lower percentage indicates greater levels of disability and/or pain. To date, no MCID has been reported for the Foot and Ankle Disability outcome measure.

The Knee Injury and Osteoarthritis Outcome Score is a five domain, patient- administered questionnaire, used to monitor disease course and outcomes following knee injury/OA or surgery. The five domains, ADL, knee-related QOL, other symptoms, pain, and sport and recreation function, are scored on a 0- 100 scale, with a higher score indicating better function and less symptoms. The MCID for the Knee Injury and Osteoarthritis Outcome Score is 10-points for each domain.

The Leeds Assessment of Neuropathic Symptoms and Signs is a self-reported questionnaire with a primary aim of distinguishing pain of a neuropathic origin, without the need for clinical assessment. The questionnaire consists of 7 questions, with a higher score suggesting the pain is predominantly of neuropathic origin. To date, no MCID has been reported for the Leeds Assessment of Neuropathic Symptoms and Signs.

The Non-Arthritic Hips Score is a 20-item, self-reported, questionnaire covering four domains (activities, function, pain and symptoms), in patients without arthritic pathology. The summative score for Non-Arthritic Hips Score is between 0-100, with 100 representing a perfectly functioning hip. The MCID for this outcome measure is 8-points.

The Victorian Institute for Sport Assessment - Achilles is a patient-reported questionnaire designed to assess the severity of Achilles tendinopathy. With questions focused on the domains of function in ADLs, pain, and sporting activity, the questionnaire is scored out of 100 (100 = asymptomatic); however, a score less than 60 is often seen in Achilles tendinopathy populations. The MCID is set at 14-points for mid-portion Achilles tendinopathy, and 6.5 points for insertional tendinopathy.

The Victorian Institute for Sport Assessment - Glutealwas designed to evaluate the severity of disability in greater trochanteric pain syndrome populations. Formulated in the same manner as other Victorian Institute of Sport Assessment tendinopathy measures, the Victorian Institute for Sport Assessment - Gluteal is scored out of 100, with a greater score associated with greater function and less symptom impairment. There is currently no MCID reported within the literature for the Victorian Institute for Sport Assessment - Gluteal.

The Victorian Institute for Sport Assessment - Hamstring was designed in the style of previous Victorian Institute of Sport Assessment tendinopathy outcome measures, but specifically to evaluate the severity of symptoms, function and ability to play sports in those with proximal hamstring tendinopathy. Scored out of 100, with higher scores being associated with greater function and less symptomatic impairments. A 4-point reduction was reported in the literature as being the threshold required to detect for true change when the standard error of measurement is considered; however, an MDIC of 22-points has been reported.

The Victorian Institute for Sport Assessment - Patella is an 8 question, patient- reported measure developed specifically to subjectively assess the severity of symptoms, function and ability to play sports in those with patella tendinopathy .

Scored out of 100, a greater score is associated with greater function and less symptom impairment, with 0 being the theoretical minimum score. The MCID for the Victorian Institute for Sport Assessment - Patella is 13-points.

The McGill Pain Questionnaire short form asks patients to rate 15 descriptors of affective and sensory feelings of pain (i.e., aching, sickening, throbbing) on a 1 (none) to 4 (severe) scale and completed a NPRS for average pain intensity. The affective and sensory section of the McGill Pain Questionnaire short form is graded from 15 to 45, with a higher score indicating a greater level of pain intensity and sensory variation; meanwhile, the NPRS of average pain is considered a separate entity. The MCID for this outcome measure is 5-points.

The Pain Catastrophizing Scale is a 13-item instrument that assesses helplessness, magnification and rumination to encompass the catastrophizing of musculoskeletal persistent pain. With each item scored 0 (not at all) to 4 (all the time), a higher score indicates greater catastrophizing of pain. A MCID of 8- and 11-points for no/low catastrophizers and catastrophizers (total score = \>30 points), respectively, has been reported within the literature.

The Tampa Scale of Kinesiophobia is a 17-item questionnaire used to evaluate kinesiophobia in people with persistent musculoskeletal pain, by assessing activity avoidance (i.e., reflects beliefs of an activity that may result in an increase of pain, or cause injury) and somatic focus (i.e., reflects beliefs and underlying of serious conditions). With each item scored 1 (strongly disagree) to 4 (strongly agree), a higher score denotes greater levels of fear of movement and/or re-injury. The MCID for Tampa Scale of Kinesiophobia is a 4-point reduction.

The Fatigue Assessment Scale is a 10-question, self-reported questionnaire that covers mental and physical fatigue. The cumulative score for the Fatigue Assessment Scale ranges from 10 to 50, with each question is scored from 1 (never) to 5 (always), with two requiring reverse scoring. A higher score indicates greater levels of fatigue, with scores \>22 representing fatigue levels are greater than "healthy" or "normal" levels. The MCID for the Fatigue Assessment Scale is 4-points.

Temporal summation is form of quantitative sensory testing that utilised mechanical pressure to gain insight to which pain mechanisms are involved for an individual patient. Temporal summation assessment resembles the "wind-up" effect, or second pain stimulus, often seen in persistent pain populations. To assess temporal summation, at a pre-determined location closest to the individuals injured site, ten consecutive ramping pulses building to the mean pressure of the respective PPT score will be applied over 5s with a 1s hold, before immediate release, with 1s rest interval before the next pulse. At the peak of each pulse, the participant will be asked to rate their pain on the NPRS scale. The first NPRS value will act as an anchor/baseline. Each NPRS will be normalised via subtraction of the initial NPRS value. To reflect changes in temporal summation across the series, the NPRS epochs (mean NPRS rating of peaks; I 2-4, II 5-7, and III 8-10) will be calculated for analysis.

Beta-endorphin is a neuropeptide produced in the central nervous system and pituitary gland in response to pain or exercise will be collected via venepuncture or cannulation to assess the acute response of BFR-RT on hypoalgesia.

Inflammatory cytokine, interleukin-6, is thought to be a driver for the development of pathological pain and has been shown to have elevated levels in persistent pain populations. This will be collected via venepuncture or cannulation to assess the response of BFR-RT on systemic inflammatory markers.

Inflammatory cytokine, tumour necrosis factor alpha, is thought to be a driver for the development of pathological pain and has been shown to have elevated levels in persistent pain populations. This will be collected via venepuncture or cannulation to assess the response of BFR-RT on systemic inflammatory markers.

The medication record sheet is utilised to show what current medications each participant is using for their pathology. The drug name, drug purpose, dose size and frequency is noted. This outcome measure is taken at baseline only (T0).

Personal and demographic characteristics including age, body height, body mass, body mass index, duration of symptoms, previous injuries, previous treatment, military occupation, duration of military service, smoking and drinking habits. This outcome measure is taken at baseline only (T0).

The Hospital Anxiety and Depression Scale (HADS) is a 14-item self-reported measure designed to assess anxiety and depression symptoms in medical patients, with emphasis on reducing the impact of physical illness on the total score. This outcome measure is taken at baseline only (T0).

The MSK-HQ is a self-reported questionnaire that allows people with musculoskeletal conditions to report their symptoms and quality of life in a standardised way. This outcome measure is taken at baseline only (T0).